Presynaptic Calcium Influx

Neurotransmitter release is triggered by calcium influx through presynaptic voltage-dependent calcium channels. Modulation of presynaptic calcium currents causes a robust alteration in synaptic efficacy. Tsujimoto et al. investigated activity-dependent facilitation of P/Q-type calcium currents at the giant nerve terminals of the calyx of Held and found that calcium current up-regulation is mediated by the calcium-binding protein NCS-1, a homolog of the Drosophila frequenin protein.